1. Field of the Invention
The invention relates to a gas precharged, liquid filling machine operating with dual rows of containers, typically used to fill a medical liquid into containers, and more particularly, to such machine operating with a pair of concentrically disposed inner and outer rows of container receptacles and corresponding gas precharged, liquid filling mechanisms which fill a liquid into containers placed on the receptacles, together with a pressurized gas.
2. Description of the Prior Art
In a conventional gas precharged, liquid filling machine, the filling liquid is transferred under pressure into a container previously filled with a pressurized gas, for example, a pressurized inert gas, while sealing the opening of the container with a packing associated with a filling nozzle. Subsequently, a snifting opening having a reduced flow area is opened to permit a gradual release of the pressurized gas within the container to the outside before the opening of the container is moved away from the packing so that the internal pressure of the container approaches atmospheric pressure before the opening moves away from the packing. In a machine of the kind described which operates with dual rows of containers, means is provided which controls the opening and closing of each valve of the inner and outer filling nozzles independently in order to accomplish the "no bottle-no filling" feature in the event only one container is supplied below a pair of inner and outer filling nozzles for some reason. However, separate control means is associated with each valve to provide an independent control Specifically, an outer valve is disposed at a low elevation with its valve opening and closing mechanism while an inner valve is disposed at a higher elevation with a separate valve opening and closing mechanism. This results in a complex arrangement of the entire valve operating mechanism. A separate snifter mechanism is associated with each of the inner and outer filling mechanisms, causing further complexity and, contributing to the size and the cost of the overall apparatus.
It will be appreciated that a gas precharged, liquid filling machine fills the liquid into the container, which is precharged with a pressurized gas, and hence it is subject to a greater degree of risk in the event of breakage of bottles than a filling machine which utilizes no pressurized gas precharge. Thus, it is highly desirable to provide some means which assures a complete elimination of the likelihood of breakage of bottles. However, the conventional arrangement provides a mechanically fixed spacing between the filling nozzles and the pair of container receptacles on which containers are placed for upward and downward movement, giving rise to the likelihood of breakage of bottles. Specifically, although a pair of inner and outer container receptacles are designed to move up and down simultaneously during their normal operation to thereby permit a common use of a single elevator for the pair of receptacles, in practice, the fixed distance between the pair of receptacles and their associated filling nozzles may cause undue stresses to be applied to and to cause damage of one of the two containers disposed between the pair of receptacles and the corresponding nozzles, due to differences in the size of similar containers or to an inadvertent mixture of containers of different sizes. The resulting breakage of containers and associated splashing of the filling liquid to be filled and the pressurized gas to the surrounding environment destroys the "no bottle-no filling" feature. As a consequence, preventing container breakage is as significant as the achievement of the "no bottle-no filling" feature.